I hope it's okay I created a new thread for this, because it's no longer about getting the model into jk2, but about texturing.

I textured my model while it was still in one piece, and it looks nice and seamless in 3DS max:

The resolution is good in 3ds Max, and for texturing the model I'm using a single 2048 x 2048 jpg. It looks fine in 3DS max also after segmenting the model, no seams can be seen.

Problem: When playing with it ingame, it is textured but the texture resolution seems a bit lower than what it appears like in 3DS max. So it seems to lose its seamlessness by showing parts of the dark untextured areas in the texture. Not so visible in these screenshots, but it gets clearer when going further away from the model for some reason. (It does not have LODs)

I understand the ideal thing would be to create a map for each different part, but I fear I would have to redo the whole process of texturing this (done in Zbrush to get it seamless)... unless anyone knows a nice solution to it? Here's a picture of the texture that is used for the whole model: